APC (Angled Physical Contact) polish refers to a connector end face that is polished at an 8° angle. This angled tip, combined with a specific end face radius, minimizes back reflection to about -60dB. APC connectors are typically green for easy identification.

UPC (Ultra Physical Contact) polish refers to a connector end face that has been polished with an extended process, resulting in a slightly more conical head shape and improved surface quality. This type of polish achieves a higher return loss (about -50dB or higher), meaning less back reflection compared to standard PC (Physical Contact) polish, which has about -40dB return loss.